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PCB 4522 Exam 2 Latest Fall/Spring Term % Guaranteed Pass
(Complete)
Which three proteins recognize various origins of replication? DnaA, protein A, ORC n eukaryotic replication, DNA polymerase _______ elongates lagging strand, and DNA polymerase _________ elongates leading strand? Delta and epsilon Initiation at oriC requires the sequential assembly of a large protein complex. Which proteins are necessary for the creation of the replication forks at oriC? DnaB, gyrase, SSB, HU Proofreading activity of DNA polymerase improves fidelity of replication by a factor of _____ fold? 100 - 500 The quick-stop conditional mutants are defective in ______? DNA polymerase C (DNA pol III, replicase) and precursors DNA polymerase I Klenow fragment is NOT used for _________. Nick translation Which proteins have helicase activity and power replisome movement at replication forks? DnaB, Mcm2-7 and Rep protein
Which protein that uniquely binds oriC is functionally analogous to the eukaryotic licensing factor? DnaA Proofreading activity of bacterial DNA polymerase I resides in the __________, and for DNA polymerase III, it's in the __________ subunit? N-terminal domain and epsilon Which answer is FALSE? DnaB propels the PhiX174 phage leading strand synthesis replication fork. Which is FALSE? The thumb domain is the most conserved in DNA. Which activity of DNA polymerase I provides proofreading during DNA replication? 3 to 5 exonuclease activity How does DnaA prevent reinitiation at the oriC until the next cell cycle? DnaA hydrolizes ATP, and this inactivates it. Which is NOT the function of eukaryotic alpha DNA polymerase? Elongates DNA Conditional mutations in which of the following would be classified as "slow-stop"? DnaA and DnaG Which is NOT part of the process of initiation of replication at oriC? Helicase DnaB unwinds DNA at the replication fork by moving along the template for the leading strand in a 3' to 5' direction.
Which is true? DNA ligase connects the 3-OH end of one Okazaki fragment to the 5 phosphate beginning of the next fragment. Which two proteins do NOT have similar functions in prokaryotes and eukaryotes? DNA polymerase III and DNA polymerase alpha Which two proteins do NOT have analogous functions in prokaryotes and eukaryotes? DNA polymerase III core and DNA polymerase beta Processivity in replication refers to_____? How well DNA polymerase stays associated with DNA template during replication Which is false? In eukaryotes, DNA polymerase I activity removes the flap(=primer-overhang) created by synthesis of the next Okazaki fragment. Which proteins are ALL components of the PhiX174 primosome? PriA, PriB, PriC, dnaT, DnaB, DnaG Which is false? DnaB loads DnaC onto the replication fork. Which is NOT the function of the replisome? It initiates synthesis of a DNA strand. DNA synthesis can NOT be initiated by the _________. DNA primer at the 5-OH
DnaB helicase cannot open dsDNA. Which protein opens dsDNA at the oriC? (melts the two strands apart) DnaA-ATP Which answer is FALSE? The primase for both PhiX174 and E. coli oriC priming is DnaA. Which is FALSE? DNA polymerase is tethered to DNA template strands through the proteins of the gamma-delta complex. Which proteins are present at the eukaryotic replication fork? DNA polymerase alpha primase, DNA polymerase delta, DNA polymerase epsilon, Mcm2- 7 helicase, PCNA Which proteins are necessary to maintain the separated strands during PhiX174 replication of the leading strand? DnaB, SSB What does NOT contribute directly to increased DNA polymerase III processivity? Displacement of gamma-delta clamp loader by DnaG Which answer is FALSE? Homologous recombination can produce 100% recombinants, since at meiosis all four chromatids undergo recombination. Homologous recombination in eukaryotes occurs_____? At meiosis in males and females in the formation of the gametes
Double stranded breaks begin in _______and recombination is complete by_________? Leptotene, late pachytene Which statement is FALSE? In allelic conversion hybrid DNA is never repaired. 5'-end capture occurs only in the ______ model? Double-strand break repair model Which statement is FALSE? In Ascomycetes tetrads, and elsewhere, allelic conversion is dependent on crossovers. Ruv _____ nicks Holliday junction and resolves it C Which is false? Zip2 protein is able to discriminate between homologous and nonhomologous chromosome pairing What happens during the RecA-mediated presynapsis stage in strand exchange? RecA and SSB act together to achieve strand invasion by coating ss DNA. Which is false? During the strand assimilation event, RecA is first bound to ds DNA, and at the end of the reaction to ss DNA. RuvC endonuclease resolves Holliday junctions according to a patch recombination model if ______?
The cuts are on the same strand, and there is no crossover Which is false? When RuvB and RuvG helicases are mutated recombination still proceeds. What happens during the RecA-mediated postsynapsis stage in strand exchange? Ss DNA replaces one strand in the ds DNA resulting in two DNAs intertwined in a joint molecule intermediate. In yeast this protein is a component of an endonuclease that resolves Holiday junctions _______? Mus Which is false? RecA hands off the 3-protruding end to RecBCD for strand invasion. What is the role of Zip2 protein in homologous pairing? It binds to ds DNA breaks and recruits the Zip1 structural protein to form the central element. RuvC endonuclease resolves Holliday junctions according to a splice recombination model if ______? The cuts are on the opposite strands, and there is crossover Which is true? RecA holds DNA in an extended helical structure different than that present in normal B DNA. Which series of events is NOT part of the process that generates 3'-protruding ends for strand invasion? RecBC cleaves 4-6 bp downstream from the chi site
Nonreplicative transposition occurs by breakage and reunion when_____? The crossover complex is nicked at the unbroken pair of donor strands What is the site necessary for the resolution of cointegrate by homologous recombination? Res site Which simple transposon contains more than one ORF=open reading frame (frameshift reads two ORFs)? IS We have an expert-written solution to this problem! What is the enzymatic activity encoded by a simple transposon? Transposase Which statement is false? During transposon insertion into the target, a small portion of the ITR sequence is duplicated. The transposase is encoded by sequence located__________? Between the ITRs =terminal inverted repeats Which is FALSE in regard to transposons? ITRs do not need to be conserved, mutations do not impair transposition. What happens when two IS elements in direct orientation located nearby recombine? Reciprocal recombination leads to the excision of the transposon and/or any material between direct repeats. What happens when two IS elements in inverted orientation located nearby recombine?
Reciprocal recombination leads to the inversion of the transposon and/or any material between direct repeats. What are transposons? Genetic elements in the genome that are mobile Transposons may serve as substrates for cellular recombination systems as _____? Portable regions of homology in reciprocal recombination Which is false? Transposon coding sequence is sequestered to the enzyme active sites while transposon ends are protruding outside of the dimer. What is the structure of a composite transposon? Chromosomal DNA flanked by two IS elements of the same type The simple transposons are called______? IS= insertion sequence Which are not transposons? iRNA= interfering RNA Which is false? Composite transposons encode DNA polymerase for replicative transposition. What is a cointegrate? In replicative transposition a strand crossover complex is formed, and transposon replication creates a cointegrate structure containing two copies of the transposon with fused donor and target DNAs.
Chromosome breakage-fusion-bridge cycle, acentric fragment is lost, if dominant alleles are lost- the recessive phenotype appears What is Hybrid Dysgenesis? A series of chromosome defects observed when a Drosophila P male is crossed with an M female Which is false? The MuDR A and MuDR B elements need to be mobilized by autonomous mutator elements Which statement is FALSE? There is an innate immunity mechanism operating in the egg of M female crossed with P male based on gene silencing and differential splicing of P element mRNA Which is false? There is an epigenetic gene silencing present in the egg of M females, which results in P cytotype. Which is false? P elements transpose only in somatic tissues. In Drosophila egg P cytotype, the repressor of P element transposition is ________? A small single-stranded RNA derived from the ds piRNA, attached to the Argonaute complex We have an expert-written solution to this problem! The transposition of Tn10 (bacteria), as well as Ac/Ds elements (maize) occurs if the donor DNA is fully methylated (state of DNA prior to replication) The transposition of Tn10 (bacteria), as well as Ac/Ds elements (maize) occurs if the donor DNA is hemimethylated (state of DNA after replication)
Which is false? Ds elements are longer than Ac because they contain various insertions of Ac sequences in them. What is the maize kernel phenotype (visual appearance) when a Ds element jumps into a gene coding for red pigmentation early in development, and then later jumps out? Yellow kernel with red-purple spots Which is true? The transposition of Tn10 (bacteria), as well as Ac/Ds elements (maize) occurs if the donor DNA is hemimethylated (state of DNA after replication). Which is false? Cellular tRNA primes retrovirus synthesis of the DNA (+) strand. What serves as a primer for the synthesis of the strong stop DNA (minus) strand? Cellular glutamine tRNA without the amino acid (uncharged) Which is false? In the model for the formation of a transducing virus, the defective and helper retrovirus RNAs are packaged into two separate virion particles which can recombine. A retrovirus infectious particle contains _____________ as its genomic component? an RNA dimer We have an expert-written solution to this problem! What can happen when a retrovirus inserts into the host genome next to a cellular oncogene and why? The U3 sequence in the downstream (right) LTR is recognized as an RNA polymerase II promoter and can initiate transcription of adjacent cellular oncogene resulting in tumorigenic growth.
Which is false? Glutamine tRNA pairs its anticodon loop with the RNA (+) strand and primes synthesis of the strong stop DNA (-) Which is false? During integration of the retrovirus linear DNA intothe host genome to form the provirus, the 5- recessed ends of LTRs are linked to staggered 3 ends of the target DNA. Which genes are NOT a part of the retroviral genome, but can be acquired by the virus? onc Which genes are NOT encoded by the yeast Ty retrotransposon? Surface protein and membrane Which statement is FALSE in regard to retrotransposons? SINES are autonomous and they encode Alu family of repeats What is the main enzymatic activity encoded by retroviruses, LTR-retrotransposons, and some non-LTR-retroposons? Reverse transcriptase Which enzyme transcribes retrotransposons into the linear DNA? Reverse transcriptase Which retrovirus gene homologies are found in LTR-retrotransposons? Reverse transcriptase, integrase, and capsid protein What is the mechanism used by the yeast Ty retrotransposon to synthesize TyA-B protein? Ribosome frameshift
What protein is uniquely encoded by non-LTR retroposons? Endonuclease Which statement is TRUE? Non-LTR retroposons and SINES have a poly A tail at the 3 end How do non-LTR retrotransposon LINES proteins assure propagation of its own functional elements? LINES nucleic acid binding proteins bind only to functional LINES RNA molecules and transfer them to the nucleus for replication and insertion into the host genome. What is "missing" from the yeast Ty virus-like particle? Surface protein and trans-membrane activity
